<?php

/*
 * Transparent SHA-256 Implementation for PHP 4 and PHP 5
 *
 * Author: Perry McGee (pmcgee@nanolink.ca)
 * Website: http://www.nanolink.ca/pub/sha256
 *
 * Copyright (C) 2006,2007,2008,2009 Nanolink Solutions
 *
 * Created: Feb 11, 2006
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation; either
 *    version 2.1 of the License, or (at your option) any later version.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.

 *    You should have received a copy of the GNU Lesser General Public
 *    License along with this library; if not, write to the Free Software
 *    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *    or see <http://www.gnu.org/licenses/>.
 *
 *  Include:
 *
 *   require_once("[path/]sha256.inc.php");
 *
 *  Usage Options:
 *
 *   1) $shaStr = hash('sha256', $string_to_hash);
 *
 *   2) $shaStr = sha256($string_to_hash[, bool ignore_php5_hash = false]);
 *
 *   3) $obj = new nanoSha2([bool $upper_case_output = false]);
 *      $shaStr = $obj->hash($string_to_hash[, bool $ignore_php5_hash = false]);
 *
 * Reference: http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html
 *
 * 2007-12-13: Cleaned up for initial public release
 * 2008-05-10: Moved all helper functions into a class.  API access unchanged.
 * 2009-06-23: Created abstraction of hash() routine
 * 2009-07-23: Added detection of 32 vs 64bit platform, and patches.
 *             Ability to define "_NANO_SHA2_UPPER" to yeild upper case hashes.
 * 2009-08-01: Added ability to attempt to use mhash() prior to running pure
 *             php code.
 *
 * NOTE: Some sporadic versions of PHP do not handle integer overflows the
 *       same as the majority of builds.  If you get hash results of:
 *        7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff
 *
 *       If you do not have permissions to change PHP versions (if you did
 *       you'd probably upgrade to PHP 5 anyway) it is advised you install a
 *       module that will allow you to use their hashing routines, examples are:
 *       - mhash module : http://ca3.php.net/mhash
 *       - Suhosin : http://www.hardened-php.net/suhosin/
 *
 *       If you install the Suhosin module, this script will transparently
 *       use their routine and define the PHP routine as _nano_sha256().
 *
 *       If the mhash module is present, and $ignore_php5_hash = false the
 *       script will attempt to use the output from mhash prior to running
 *       the PHP code.
 */
 
/*
 * Modifications by Joseph T. Parsons for FreezeMessenger
 * 2012-07-02: Removed extra layers used to make access to the class transparent.
 */

class nanoSha2
{
      // php 4 - 5 compatable class properties
      var     $toUpper;
      var     $platform;

      // Php 4 - 6 compatable constructor
      function nanoSha2($toUpper = false) {
	  // Determine if the caller wants upper case or not.
	  $this->toUpper = is_bool($toUpper)
			  ? $toUpper
			  : ((defined('_NANO_SHA2_UPPER')) ? true : false);

	  // Deteremine if the system is 32 or 64 bit.
	  $tmpInt = (int)4294967295;
	  $this->platform = ($tmpInt > 0) ? 64 : 32;
      }

      // Do the SHA-256 Padding routine (make input a multiple of 512 bits)
      function char_pad($str)
      {
	  $tmpStr = $str;

	  $l = strlen($tmpStr)*8;     // # of bits from input string

	  $tmpStr .= "\x80";          // append the "1" bit followed by 7 0's

	  $k = (512 - (($l + 8 + 64) % 512)) / 8;   // # of 0 bytes to append
	  $k += 4;    // PHP Strings will never exceed (2^31)-1, 1st 32bits of
		      // the 64-bit value representing $l can be all 0's

	  for ($x = 0; $x < $k; $x++) {
	      $tmpStr .= "\0";
	  }

	  // append the 32-bits representing # of bits from input string ($l)
	  $tmpStr .= chr((($l>>24) & 0xFF));
	  $tmpStr .= chr((($l>>16) & 0xFF));
	  $tmpStr .= chr((($l>>8) & 0xFF));
	  $tmpStr .= chr(($l & 0xFF));

	  return $tmpStr;
      }

      // Here are the bitwise and functions as defined in FIPS180-2 Standard
      function addmod2n($x, $y, $n = 4294967296)      // Z = (X + Y) mod 2^32
      {
	  $mask = 0x80000000;

	  if ($x < 0) {
	      $x &= 0x7FFFFFFF;
	      $x = (float)$x + $mask;
	  }

	  if ($y < 0) {
	      $y &= 0x7FFFFFFF;
	      $y = (float)$y + $mask;
	  }

	  $r = $x + $y;

	  if ($r >= $n) {
	      while ($r >= $n) {
		  $r -= $n;
	      }
	  }

	  return (int)$r;
      }

      // Logical bitwise right shift (PHP default is arithmetic shift)
      function SHR($x, $n)        // x >> n
      {
	  if ($n >= 32) {      // impose some limits to keep it 32-bit
	      return (int)0;
	  }

	  if ($n <= 0) {
	      return (int)$x;
	  }

	  $mask = 0x40000000;

	  if ($x < 0) {
	      $x &= 0x7FFFFFFF;
	      $mask = $mask >> ($n-1);
	      return ($x >> $n) | $mask;
	  }

	  return (int)$x >> (int)$n;
      }

      function ROTR($x, $n) { return (int)(($this->SHR($x, $n) | ($x << (32-$n)) & 0xFFFFFFFF)); }
      function Ch($x, $y, $z) { return ($x & $y) ^ ((~$x) & $z); }
      function Maj($x, $y, $z) { return ($x & $y) ^ ($x & $z) ^ ($y & $z); }
      function Sigma0($x) { return (int) ($this->ROTR($x, 2)^$this->ROTR($x, 13)^$this->ROTR($x, 22)); }
      function Sigma1($x) { return (int) ($this->ROTR($x, 6)^$this->ROTR($x, 11)^$this->ROTR($x, 25)); }
      function sigma_0($x) { return (int) ($this->ROTR($x, 7)^$this->ROTR($x, 18)^$this->SHR($x, 3)); }
      function sigma_1($x) { return (int) ($this->ROTR($x, 17)^$this->ROTR($x, 19)^$this->SHR($x, 10)); }

      /*
	* Custom functions to provide PHP support
	*/
      // split a byte-string into integer array values
      function int_split($input)
      {
	  $l = strlen($input);

	  if ($l <= 0) {
	      return (int)0;
	  }

	  if (($l % 4) != 0) { // invalid input
	      return false;
	  }

	  for ($i = 0; $i < $l; $i += 4)
	  {
	      $int_build  = (ord($input[$i]) << 24);
	      $int_build += (ord($input[$i+1]) << 16);
	      $int_build += (ord($input[$i+2]) << 8);
	      $int_build += (ord($input[$i+3]));

	      $result[] = $int_build;
	  }

	  return $result;
      }

      /**
	* Process and return the hash.
	*
	* @param $str Input string to hash
	* @return string Hexadecimal representation of the message digest
	*/
      function hash($str, $ig_func = false)
      {
	  unset($binStr);     // binary representation of input string
	  unset($hexStr);     // 256-bit message digest in readable hex format

	  /*
	    * SHA-256 Constants
	    *  Sequence of sixty-four constant 32-bit words representing the
	    *  first thirty-two bits of the fractional parts of the cube roots
	    *  of the first sixtyfour prime numbers.
	    */
	  $K = array((int)0x428a2f98, (int)0x71374491, (int)0xb5c0fbcf,
		      (int)0xe9b5dba5, (int)0x3956c25b, (int)0x59f111f1,
		      (int)0x923f82a4, (int)0xab1c5ed5, (int)0xd807aa98,
		      (int)0x12835b01, (int)0x243185be, (int)0x550c7dc3,
		      (int)0x72be5d74, (int)0x80deb1fe, (int)0x9bdc06a7,
		      (int)0xc19bf174, (int)0xe49b69c1, (int)0xefbe4786,
		      (int)0x0fc19dc6, (int)0x240ca1cc, (int)0x2de92c6f,
		      (int)0x4a7484aa, (int)0x5cb0a9dc, (int)0x76f988da,
		      (int)0x983e5152, (int)0xa831c66d, (int)0xb00327c8,
		      (int)0xbf597fc7, (int)0xc6e00bf3, (int)0xd5a79147,
		      (int)0x06ca6351, (int)0x14292967, (int)0x27b70a85,
		      (int)0x2e1b2138, (int)0x4d2c6dfc, (int)0x53380d13,
		      (int)0x650a7354, (int)0x766a0abb, (int)0x81c2c92e,
		      (int)0x92722c85, (int)0xa2bfe8a1, (int)0xa81a664b,
		      (int)0xc24b8b70, (int)0xc76c51a3, (int)0xd192e819,
		      (int)0xd6990624, (int)0xf40e3585, (int)0x106aa070,
		      (int)0x19a4c116, (int)0x1e376c08, (int)0x2748774c,
		      (int)0x34b0bcb5, (int)0x391c0cb3, (int)0x4ed8aa4a,
		      (int)0x5b9cca4f, (int)0x682e6ff3, (int)0x748f82ee,
		      (int)0x78a5636f, (int)0x84c87814, (int)0x8cc70208,
		      (int)0x90befffa, (int)0xa4506ceb, (int)0xbef9a3f7,
		      (int)0xc67178f2);

	  // Pre-processing: Padding the string
	  $binStr = $this->char_pad($str);

	  // Parsing the Padded Message (Break into N 512-bit blocks)
	  $M = str_split($binStr, 64);

	  // Set the initial hash values
	  $h[0] = (int)0x6a09e667;
	  $h[1] = (int)0xbb67ae85;
	  $h[2] = (int)0x3c6ef372;
	  $h[3] = (int)0xa54ff53a;
	  $h[4] = (int)0x510e527f;
	  $h[5] = (int)0x9b05688c;
	  $h[6] = (int)0x1f83d9ab;
	  $h[7] = (int)0x5be0cd19;

	  // loop through message blocks and compute hash. ( For i=1 to N : )
	  $N = count($M);
	  for ($i = 0; $i < $N; $i++)
	  {
	      // Break input block into 16 32bit words (message schedule prep)
	      $MI = $this->int_split($M[$i]);

	      // Initialize working variables
	      $_a = (int)$h[0];
	      $_b = (int)$h[1];
	      $_c = (int)$h[2];
	      $_d = (int)$h[3];
	      $_e = (int)$h[4];
	      $_f = (int)$h[5];
	      $_g = (int)$h[6];
	      $_h = (int)$h[7];
	      unset($_s0);
	      unset($_s1);
	      unset($_T1);
	      unset($_T2);
	      $W = array();

	      // Compute the hash and update
	      for ($t = 0; $t < 16; $t++)
	      {
		  // Prepare the first 16 message schedule values as we loop
		  $W[$t] = $MI[$t];

		  // Compute hash
		  $_T1 = $this->addmod2n($this->addmod2n($this->addmod2n($this->addmod2n($_h, $this->Sigma1($_e)), $this->Ch($_e, $_f, $_g)), $K[$t]), $W[$t]);
		  $_T2 = $this->addmod2n($this->Sigma0($_a), $this->Maj($_a, $_b, $_c));

		  // Update working variables
		  $_h = $_g; $_g = $_f; $_f = $_e; $_e = $this->addmod2n($_d, $_T1);
		  $_d = $_c; $_c = $_b; $_b = $_a; $_a = $this->addmod2n($_T1, $_T2);
	      }

	      for (; $t < 64; $t++)
	      {
		  // Continue building the message schedule as we loop
		  $_s0 = $W[($t+1)&0x0F];
		  $_s0 = $this->sigma_0($_s0);
		  $_s1 = $W[($t+14)&0x0F];
		  $_s1 = $this->sigma_1($_s1);

		  $W[$t&0xF] = $this->addmod2n($this->addmod2n($this->addmod2n($W[$t&0xF], $_s0), $_s1), $W[($t+9)&0x0F]);

		  // Compute hash
		  $_T1 = $this->addmod2n($this->addmod2n($this->addmod2n($this->addmod2n($_h, $this->Sigma1($_e)), $this->Ch($_e, $_f, $_g)), $K[$t]), $W[$t&0xF]);
		  $_T2 = $this->addmod2n($this->Sigma0($_a), $this->Maj($_a, $_b, $_c));

		  // Update working variables
		  $_h = $_g; $_g = $_f; $_f = $_e; $_e = $this->addmod2n($_d, $_T1);
		  $_d = $_c; $_c = $_b; $_b = $_a; $_a = $this->addmod2n($_T1, $_T2);
	      }

	      $h[0] = $this->addmod2n($h[0], $_a);
	      $h[1] = $this->addmod2n($h[1], $_b);
	      $h[2] = $this->addmod2n($h[2], $_c);
	      $h[3] = $this->addmod2n($h[3], $_d);
	      $h[4] = $this->addmod2n($h[4], $_e);
	      $h[5] = $this->addmod2n($h[5], $_f);
	      $h[6] = $this->addmod2n($h[6], $_g);
	      $h[7] = $this->addmod2n($h[7], $_h);
	  }

	  // Convert the 32-bit words into human readable hexadecimal format.
	  $hexStr = sprintf("%08x%08x%08x%08x%08x%08x%08x%08x", $h[0], $h[1], $h[2], $h[3], $h[4], $h[5], $h[6], $h[7]);

	  return ($this->toUpper) ? strtoupper($hexStr) : $hexStr;
      }
}

?>